Micropropagation of clones from controlled crosses of Gmelina arborea in Costa Rica

Seeds of 10 families of Gmelina arborea (gmelina) obtained from controlled crosses, were established in vitro. Nodal segments of seedlings were placed in Murashige and Skoog (MS) (1962) basal medium supplemented with different concentrations of benzyladenine (BA). The shoots were separated and placed in another MS (1962) medium supplemented with indolebutyric acid (IBA). The shoots were transferred to Jiffy® pellets of sphagnum moss (compressed peat) and were placed in a growth chamber where they stayed for a period of 15 days. Afterwards, the plant material was placed in a greenhouse for 20 days. Significant differences were observed in the bud induction rate and in the rooting percentages of families and genotypes. The use of Jiffy® pellets diminished the loss of plant material due to contamination, improved rooting of shoots and the survival of plants in the greenhouse conditions and the field. Palabras clave: Cruces controlados, Cultivo de tejidos, Gmelina arborea, Micropropagación Resumen. Se establecieron in vitro semillas de diez familias de melina producto de cruces controlados. Los segmentos nodales de las plántulas fueron colocados en un medio de cultivo MS (1962) suplementado con diferentes concentraciones de benciladenina (BA). Los brotes se separaron y se colocaron en otro medio de cultivo MS (1962) suplementado con diferentes concentraciones de ácido indolbutírico (AIB). Los tallos se transfirieron a Jiffy (comprimidos de turba), que fueron colocados en una cámara de crecimiento donde permanecieron por un período de 15 días. Posteriormente, se trasladaron al invernadero para su aclimatación por un período de 20 días. Se observaron diferencias significativas en la tasa de inducción de brotes y en el porcentaje de enraizamiento entre familias y entre genotipos. El empleo de Jiffys disminuyó pérdidas por contaminación, mejoró sustancialmente el enraizamiento de los tallos y con ello la supervivencia de las plantas en vivero y en el campo.     

A New Species of Mugilicola Parasitic on South African Elvers (Copepoda,Therodamasidae)

A new species of parasitic copepod belonging to the genus Mugilicola Tripathi, I960 (CYCLOPOIDA: THERODAMASIDAE) is described. The copepods were embedded in the buccal cavity of elvers of Anguilla mossambica caught in South African rivers.     

Venus southern hemisphere: geologic character and age of terrains in the themis-alpha-lada region

Arecibo high-resolution radar images of the southern hemisphere of Venus extending to 78 degrees S show that the surface of the Themis-Alpha-Lada region is characterized by linear deformation zones with volcanoes and corona-like features and by regional volcanic deposits (primarily plains, small shields, and large edifices). Large-scale areal deformation is limited to the tessera of Alpha Regio. Lada Terra, in the southern high latitudes, contains several large coronae, in contrast to Ishtar Terra in the northern high latitudes. The density of craters of possible impact origin is somewhat lower than that observed in the Venera 15 and 16 coverage; these data extend to 43 percent of the areas of the surface of Venus with ages of less than about 1 billion years.     

Radar Image of Asteroid 1989 PB

Radar observations of the near-Earth asteroid 1989 PB, made shortly after its optical discovery, yield a sequence of delay-Doppler images that reveal it to consist of two distinct lobes that appear to be in contact. It seems likely that the two lobes once were separate and that they collided to produce the current "contact-binary" configuration.